The present invention relates to a video signal processing system and, more particularly, to a special video effect system for combining video signals while compression, enlargement or rotation processing is being applied thereto.
In a special video effect system for television broadcasting, a plurality of video signals are frequently combined on a TV picture screen by using a key signal. Further, by using a digital process, various special effects such as the compression, enlargement and rotation of a picture are frequently performed. Therefore, when the video signals are to be combined, such digital processes may be used. In this case, it is necessary to produce a special key signal for the combination of video signals in accordance with a desired special effect. A prior art special effect system includes a digital special effect unit for special video processing, a key signal generating unit and a a micro-computer (CPU) for controlling the two units. The CPU provides a control signal to a digital special effect unit and a key signal generating unit so that the desired special effect can be produced. In the digital special effect unit, special video processing corresponding to the desired special effect is performed in response to the control signal. In the key signal generating unit, a key signal suitable to the desired special effect is also generated in response to the control signal. In the key signal generating unit, a large-scale circuit configuration is not required when the desired special effect is relatively simple, for example, a wiping effect in the horizontal and/or vertical direction. However, when the desired special effect is complicated as, for example, when accompanied by a rotation process and a tilting process, the key signal generating unit according to the prior art is quite complicated and as complicated as the special effect unit.